The present invention relates to methods and devices for closing a body lumen, tissue opening, or cavity and, in particular, for closing an atrial septal defect.
Embolic stroke is the nation""s third leading killer for adults, and is a major cause of disability. There are over 700,000 strokes per year in the United States alone. Of these, roughly 100,000 are hemoragic, and 600,000 are ischemic (either due to vessel narrowing or to embolism). The most common cause of embolic stroke emanating from the heart is thrombus formation due to atrial fibrillation. Approximately 80,000 strokes per year are attributable to atrial fibrillation. Atrial fibrillation is an arrhythmia of the heart that results in a rapid and chaotic heartbeat that produces lower cardiac output and irregular and turbulent blood flow in the vascular system. There are over five million people worldwide with atrial fibrillation, with about four hundred thousand new cases reported each year. Atrial fibrillation is associated with a 500 percent greater risk of stroke due to the condition. A patient with atrial fibrillation typically has a significantly decreased quality of life due, in part, to the fear of a stroke, and the pharmaceutical regimen necessary to reduce that risk.
For patients who develop atrial thrombus from atrial fibrillation, the clot normally occurs in the left atrial appendage (LAA) of the heart. The LAA is a cavity which looks like a small finger or windsock and which is connected to the lateral wall of the left atrium between the mitral valve and the root of the left pulmonary vein. The LAA normally contracts with the rest of the left atrium during a normal heart cycle, thus keeping blood from becoming stagnant therein, but often fails to contract with any vigor in patients experiencing atrial fibrillation due to the discoordinate electrical signals associated with AF. As a result, thrombus formation is predisposed to form in the stagnant blood within the LAA.
Blackshear and Odell have reported that of the 1288 patients with non-rheumatic atrial fibrillation involved in their study, 221 (17%) had thrombus detected in the left atrium of the heart. Blackshear J. L., Odell J. A., Appendage Obliteration to Reduce Stroke in Cardiac Surgical Patients With Atrial Fibrillation. Ann Thorac. Surg., 1996.61(2):755-9. Of the patients with atrial thrombus, 201 (91%) had the atrial thrombus located within the left atrial appendage. The foregoing suggests that the elimination or containment of thrombus formed within the LAA of patients with atrial fibrillation would significantly reduce the incidence of stroke in those patients.
Pharmacological therapies for stroke prevention such as oral or systemic administration of warfarin or the like have been inadequate due to serious side effects of the medications and lack of patient compliance in taking the medication. Invasive surgical or thorascopic techniques have been used to obliterate the LAA, however, many patients are not suitable candidates for such surgical procedures due to a compromised condition or having previously undergone cardiac surgery. In addition, the perceived risks of even a thorascopic surgical procedure often outweigh the potential benefits. See Blackshear and Odell, above. See also Lindsay B. D., Obliteration of the Left Atrial Appendage: A Concept Worth Testing, Ann Thorac. Surg., 1996.61(2):515.
Despite the various efforts in the prior art, there remains a need for a minimally invasive method and associated devices for reducing the risk of thrombus formation in the left atrial appendage.
Other conditions which would benefit from a tissue aperture closure catheter are tissue openings such as an atrial septal defect. In general, the heart is divided into four chambers, the two upper being the left and right atria and the two lower being the left and right ventricles. The atria are separated from each other by a muscular wall, the interatrial septum, and the ventricles by the interventricular septum.
Either congenitally or by acquisition, abnormal openings, holes or shunts can occur between the chambers of the heart or the great vessels (interatrial and interventricular septal defects or patent ductus arteriosus and aorthico-pulmonary window respectively), causing shunting of blood through the opening. The ductus arteriosus is the prenatal canal between the pulmonary artery and the aortic arch which normally closes soon after birth. The deformity is usually congenital, resulting from a failure of completion of the formation of the septum, or wall, between the two sides during fetal life when the heart forms from a folded tube into a four-chambered, two unit system.
These deformities can carry significant sequelae. For example, with an atrial septal defect, blood is shunted from the left atrium of the heart to the right, producing an over-load of the right heart. In addition to left-to-right shunts such as occur in patent ductus arteriosus from the aorta to the pulmonary artery, the left side of the heart has to work harder because some of the blood which it pumps will recirculate through the lungs instead of going out to the rest of the body. The ill effects of these lesions usually cause added strain on the heart with ultimate failure if not corrected.
Previous extracardiac (outside the heart) or intracardiac septal defects have required relatively extensive surgical techniques for correction. To date the most common method of closing intracardiac shunts, such as atrial-septal defects and ventricular-septal defects, entails the relatively drastic technique of open-heart surgery, requiring opening the chest or sternum and diverting the blood from the heart with the use of a cardiopulmonary bypass. The heart is then opened, the defect is sewn shut by direct suturing with or without a patch of synthetic material (usually of Dacron, Teflon, silk, nylon or pericardium), and then the heart is closed. The patient is then taken off the cardiopulmonary bypass machine, and then the chest is closed.
In place of direct suturing, closures of interauricular septal defects by means of a mechanical prosthesis have been disclosed.
U.S. Pat. No. 3,874,388 to King, et al. relates to a shunt defect closure system including a pair of opposed umbrella-like elements locked together in a face to face relationship and delivered by means of a catheter, whereby a defect is closed. U.S. Pat. No. 5,350,399 to Erlebacher, et al. relates to a percutaneous arterial puncture seal device also including a pair of opposed umbrella-like elements and an insertion tool.
U.S. Pat. No. 4,710,192 to Liotta, et al. relates to a vaulted diaphragm for occlusion in a descending thoracic aorta.
U.S. Pat. No. 5,108,420 to Marks relates to an aperture occlusion device consisting of a wire having an elongated configuration for delivery to the aperture, and a preprogrammed configuration including occlusion forming wire segments on each side of the aperture.
U.S. Pat. No. 4,007,743 to Blake relates to an opening mechanism for umbrella-like intravascular shunt defect closure device having foldable flat ring sections which extend between pivotable struts when the device is expanded and fold between the struts when the device is collapsed.
Notwithstanding the foregoing, there remains a need for a transluminal method and apparatus for correcting intracardiac septal defects, which enables a patch to placed across a septal defect to inhibit or prevent the flow of blood therethrough.
The present invention provides a closure catheter and methods for closing an opening in tissue, a body lumen, hollow organ or other body cavity. The catheter and methods of its use are useful in a variety of procedures, such as treating (closing) wounds and naturally or surgically created apertures or passageways. Applications include, but are not limited to, atrial septal defect closure, patent ductus arteriosis closure, aneurysm isolation and graft and/or bypass anastomosis procedures.
There is provided in accordance with one aspect of the present invention, a method of patching an intracardiac septal defect such as an atrial septal defect. The method comprises the steps of providing a catheter having an elongate flexible body with a proximal end and a distal end, a patch and at least two anchors removably carried by the distal end. The distal end is advanced to a position near the atrial septal defect, and the patch is positioned across the defect. The anchors are thereafter deployed from the catheter to secure the patch across the defect.
In one embodiment, the positioning step comprises enlarging the cross section of the patch from a reduced profile for advancing the catheter, to an enlarged profile for patching the defect. The positioning step comprises inclining at least one patch support from an axial orientation to an inclined orientation to position the patch across the defect. The positioning step preferably comprises inclining at least three patch supports from an axial orientation to an inclined orientation to position the patch across the defect. In one embodiment, the deploying the anchors step comprises advancing the anchors distally through the patch and into tissue adjacent the defect to secure the patch across the defect.
In accordance with another aspect of the present invention, there is provided a method of closing an opening in a subcutaneous tissue plane. The method comprises the steps of providing a catheter having a patch and at least one anchor. The catheter is advanced to the opening, and the patch is positioned across the opening. The anchor is advanced into tissue to secure the patch across the opening. Preferably, the advancing the anchor step comprises advancing at least three anchors into the tissue to secure the patch across the opening. The opening may be a naturally occurring opening such as an atrial septal defect, or a surgically created opening.
In accordance with a further aspect of the present invention, there is provided a deployment catheter for deploying a patch across a tissue aperture. The deployment catheter comprises an elongate body having a proximal end and a distal end. At least one patch support is provided on the body for removably carrying a patch. At least one anchor support is also provided for removably carrying at least one anchor. The anchor support is movable between an axial orientation and an inclined orientation with respect to a longitudinal axis of the body. In one embodiment, the anchor support is hingably connected to the patch support. The anchor support and patch support may also be the same structure, such that the patch is carried by the anchor supports. Preferably, at least three anchor supports and/or at least three patch supports are provided.
In accordance with a further aspect of the present invention, there is provided a patch deployment catheter for deploying a patch across an opening. The catheter comprises an elongate body, having a proximal end and a distal end. At least two supports are provided on the catheter, movable between an axial orientation and an inclined orientation. Each support comprises a proximal section, a distal section and a hinge in-between. A control is provided on the catheter for moving the hinge radially outwardly from a first position for introducing the catheter to a site in the body to a second position for deploying the patch at the site. The supports are in the axial orientation when the hinge is in the first position.
In one embodiment, the elongate body is flexible. Preferably, at least one tissue anchor is carried by the proximal section of each support. At least one patch is preferably carried by the distal section of each support. In one embodiment, the patch comprises a tissue ingrowth surface.
Further features and advantages of the present invention will become apparent to those of skill in the art in view of the detailed description of preferred embodiments which follows, when considered together with the attached drawings and claims.